NSF/ANSI Standard 177: A Level Playing Field for Shower Filter Claims
As consumers become more educated about water quality, they have begun to regularly install a host of treatment systems: water softeners, carbon filters and reverse osmosis units, to name a few.
As water filtration systems have become more advanced, so, too, have consumers' needs. Despite the increased use of both point-of-use and point-of-entry water treatment systems in many homes, an increasing number of consumers complained about the effects of chlorine in their shower water. In response to consumer demands, water treatment system manufacturers developed shower filtration systems to reduce the presence of chlorine in shower water.
As a wide variety of shower filters became popular, so did a wide variety of test procedures to verify performance claims. Without a national standard, however, manufacturers could use any method they chose to establish performance claims.
The industry recognized the need for a standard testing procedure to verify free available chlorine (FAC) reduction claims. With the introduction of a national standard, all manufacturers now are using the same methodology to establish FAC reduction performance for their systems, resulting in a true “apples to apples” comparison.
NSF International developed NSF/ANSI 177, Shower Filtration Systems - Aesthetic Effects, through an American National Standards Institute accredited consensus process. NSF/ANSI 177 establishes minimum certification requirements for shower filters: material safety, structural integrity, minimum flow rate, FAC reduction and literature.
A shower filter is defined as a point-of-use system used for the reduction of substances affecting aesthetic qualities of shower water. Shower filters are not considered drinking water treatment units. Shower water is considered potable and for bathing purposes only, not for consumption. Standard 177 applies only to complete shower filter systems, components or systems with functions covered by other relevant NSF/ANSI standards will be certified accordingly.
The TestsThe material safety requirements of NSF/ANSI 177 are straightforward: a formulation review of all parts in contact with shower water and system production methods. A system is compliant with NSF/ANSI 177 if no materials include lead as an intentional ingredient, with the exception of “lead-free” brass, and production methods do not use solvent bonding. No testing is required.
Both a hydrostatic and cyclic pressure tests are required to determine the structural integrity of the complete shower filter system. The system design determines the testing pressures.
All systems must be designed to withstand a pressure of 125 psi or the maximum working pressure, whichever is greater. Hot water is used during structural integrity testing to simulate actual use. The hydrostatic pressure test uses water at 120 degrees F. The cycle test uses water at 104 degrees +/- 4 degrees F. One complete system is used for each test. The tested system must remain watertight throughout the test for passing results.
Systems making the FAC reduction claim must reduce the influent challenge of 2.0 mg/l chlorine by 50 percent during the FAC reduction test. The influent challenge water for the FAC reduction test will be water from a public supply with the characteristics specified in Table 1. If public water supply with these characteristics is not available, other set procedures will be taken to modify an alternate water supply.
Table 1: FAC Reduction Test Water CharacteristicsPH - - 7.5 +/- 0.5
Temperature -- 40 +/- 2C(104 +/- 4 F)
Total Dissolved Solids (TDS) -- 200-500 mg/L
Total Organic Carbons (TOC) -- greater than or equal to 1.0 mg/L
Turbidity -- less than 1 NTU
Free Available Chlorine -- 2 mg/L +/- 0.2 mg/L
Chloramines, total -- les than 0.1 mg/L
FAC ReductionThe test uses two systems that are flushed and conditioned according to the manufacturer's instructions with test challenge water for the FAC reduction test. The test is run at the manufacturer's suggested flow rate. This flow rate must be at least 1 gpm at an initial dynamic pressure of 80 psi. If, during the FAC reduction test, the flow rate drops below 1 gpm the test will be stopped. The pressure will not be adjusted during the test. Systems run 15 minutes on and 15 minutes off (50/50 cycle) for a 16-hour period with an eight-hour rest period.
After the conditioning procedure, the first influent and effluent samples are taken after 10 unit volumes have passed through the system. Samples are then taken at 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100 percent of the estimated capacity during the last minute of the 15-minute cycle when water flows through the system. Extra sample points may be requested beyond the estimated capacity to determine the effective life of the system.
Care is taken to avoid aeration of the samples, and collection procedures are specific in order to minimize this risk.
Influent samples are collected immediately upstream of the test systems through a pressurized manifold. Effluent samples are collected no more than 1 ft. from the showerhead. Product water samples are analyzed within one minute of collection. Spectrophometric sample analysis is the recommended analytical method.
The last of at least five consecutive passing sample points (reduction of influent challenge level by 50 percent) determines capacity. This value can be greater than or less than the manufacturer's estimated capacity.
With both the shower filter capacity and rated service flow confirmed by the FAC reduction test, the manufacturer will now have all required information for the NSF/ANSI 177-compliant literature.
Product LiteratureNSF/ANSI 177 specifies information to be provided on the owner's manual, performance data sheet, data plate and replacement component packaging. Each type of product literature requires the model name and number and contact information of the manufacturer. The owner's manual also must include installation and operation instructions of the shower filter, flushing and conditioning procedures (identical to those used for testing), rated capacity, rated service flow rate, maximum working pressure, and maximum operating temperature.
The owner's manual must state that the system conforms to NSF/ANSI 177 for the reduction of FAC. The owner's manual also must include statements noting that the installation of the certified shower filter must comply with applicable plumbing codes and that the system is not intended as a drinking water treatment system.
The data plate requires much of the same information as the owner's manual, with an additional statement discerning testing under laboratory conditions and actual performance The following is the required statement for claims on the performance data sheet:
- “This system has been tested according to NSF/ANSI 177 for reduction of free available chlorine. The concentration of free available chlorine in water entering the system was reduced to a concentration less that nor equal to the permissible limit for water leaving the system, as specified in NSF/ANSI 177. This system has not been evaluated for free available chlorine reduction performance in the presence of chloramines. Free available chlorine reduction performance may be impacted by the presence of chloramines in the water supply. Please contact your local water utility to determine if chloramines are used in treating your water.”
NSF/ANSI 177 provides an industry answer to concerns over validating shower filter performance claims. Minimum requirements are specified for material safety, structural integrity, FAC reduction and literature. The FAC reduction test requires all manufacturers making this claim to verify performance through the same test protocol.
Would You Wash Your Hair In A Swimming Pool?Anyone who's spent too much time in a swimming pool knows that the chlorinated water can dry out skin and hair and leave eyes red and sore.
Chlorine is a fact of life for municipal water systems - because it works so well in treating water. But just as some consumers are concerned enough to filter chlorine from drinking water, many are just as concerned about getting rid of chlorine from their daily shower.
Manufacturers of chlorine filters for showers say users can notice a difference after one use. Chlorine readily bonds to organic matter, such as skin and hair, destroying the natural bacterial balance, which can cause dryness, itching and flaking. But by filtering the chlorine out, hair is more manageable, and color-treated hair will fade less. Skin is left less dry, too.
Besides cosmetic concerns about skin and hair care, chlorine can cause health problems when inhaled. Inhaling shower water also allows exposure to volatile organic chemicals, which can cause problems for asthmatics, but also children and the elderly regardless of allergies.
Keep in mind NSF/ANSI Standard 177 is not a health effects standard, so any issues with potential health effects of chlorine exposure are not covered in this certification.